身份证号过滤

	private static int[] weight = { 7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2 };
	private static char[] validate = { '1', '0', 'X', '9', '8', '7', '6', '5', '4', '3', '2' };
	private static boolean isIdCard(String card) {
		if (card == null)
			return false;
		card = card.trim() ;
		if(card.length() == 15){
			for(char d : card.toCharArray()){
				if(!('0' <= d && d <= '9') )
					return false ; 
			}
			return true ;
		}
		else if (card.length() == 18) {
			int sum = 0;
			for(char d : card.toCharArray()){
				if(!( ('0' <= d && d <= '9') || d == 'x' || d == 'X' ) )
					return false ; 
			}
			for(int i = 0; i < card.length() - 1 ; i++) {
				char d = card.charAt(i) ;
				if('0' <= d && d <= '9'){
				   sum = sum + (d - '0') * weight[i] ;
				}
				else return false ;
			}
			if (validate[sum % 11] == card.charAt(17)) {
				return true;
			}
		}
		return false;
	}
	
	public static String filterIdCard(String str){
		if(str == null) return null ;
		StringBuilder builder = new StringBuilder()  ;
		int n = str.length() ;
		boolean[] vis = new boolean[n] ;
		Arrays.fill(vis , false) ;
		for(int i = 0 ; i < n  ; i++){
			char d = str.charAt(i) ;
			if('0' <= d && d <= '9' && !vis[i]){
			   if(i + 18 <= n && isIdCard(str.substring(i, i+18))){
				   Arrays.fill(vis, i, i+18 , true) ;
				   builder.append("****") ;
			   }
			   else if(i + 15 <= n && isIdCard(str.substring(i, i+15))){
				   Arrays.fill(vis, i, i+15 , true) ;
				   builder.append("****") ;
		       }	
			}
			if(!vis[i]) builder.append(str.charAt(i)) ;
		}
		return builder.toString() ; 
	}